Is that finished work of redemption sufficient to keep you saved to the uttermost? Peter said in 1 Peter 1:5 that we are "kept by the power of God"...it is God who keeps us...not ourselves.
1 Peter 1:5 Who are kept by the power of God through faith unto salvation ready to be revealed in the last time.
Also, Ephesians 1:13-14 says:
Ephesians 1:13 In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise,
Ephesians 1:14 Which is the earnest of our inheritance until the redemption of the purchased possession, unto the praise of his glory.
No man is able to break that "seal"....if man could break this "seal", then God's power is unable to "keep us sealed"....however, that is not what God's Word says.
John 10:27 My sheep hear my voice, and I know them, and they follow me:
John 10:28 And I give unto them eternal life; and they shall never perish, neither shall any man pluck them out of my hand.
John 10:29 My Father, which gave them me, is greater than all; and no man is able to pluck them out of my Father's hand.